Fluid heater



G. B. COOK FLUID HEATER Nov. 17, 1931.

Filed March 28. 1950 in-21 I I N VEN TOR.

A TTORNE Y.

40 vertical direction to each other.

Patented Nov. 17, 1931 UNITED STATES rrxrerrrv OFFICE] GEORGE B. COOK, F ELIZABETH, NEW JERSEY, ASSIGNOR TO STANDARD OIL DEVELOP- MENT COMPANY A CORPORATION, OF DELAWARE FLUID HEATER Application filed March 28,1930. Serial No. 439,678.

Fig. 1 is a diagrammatic vertical section and elevation through part of the furnace, showing the arrangement of the tubes and flow of the fluid therein viewed from one side of the furnace;

Fig. 2 is a similar section showing the same arrangement and flow as seen from the other side of the furnace; and

Fig. 3 is a diagrammatic vertical section and elevation through the Whole length of the furnace, showing the arrangement of the heating tubes according to the invention and their connection with the two sets of tubes in the convection heat sect-ion.

It is often necessary in fluid heaters to pro- 26 vide a double" circuit of flow in the radiant heat section because one circuit of flow will require, at the given feed rate, too large a diameter of the tubes to be used with safety against bursting of the tubes under the de- 30 sired conditions of temperature and pressure. It is, of course, a primary requirement that the heat input and fluid flow be equal in both branches ,of the double circuit. An advantageous arrangement of the tubes and the header boxes forms the subject matter of this invention, the main object of which is to provide such arrangement using two nearly horizontal rows of tubes, the individual members of the two rows being aligned in \Vhen the invention is applied to cracking coils, used to heat the oil to cracking temperature, the following objects and advantages ivill be real ized by the invention:

1. Equal heat input in each circuit.

2. Equal pressure drop in each circuit. 3. Equal velocity of the fluid in each circuit.

4. Equal throughout in each circuit.

5. Equal cracking in each circuit.

- In the figures the numerals 1 and 2 designate'the two circuits. One circuit includes a series of connected tubes 1a and 1?) extending parallel to and spaced with respect to each other in vertically spaced substantially horizontal rows in the combustion chamber. The upper tubes lb are connected to the lower tubes 1a in series by an appropriate fitting such as header boxes 3. A second series of similarly connected tubes 2a and 2b ofsubstantially the same internal diameter as tubes 1a and 1b are disposed in the spaces between and substantially parallel with the tubes 1a and 1b in the rows. There may be two separate feed pumps 4 and 5 in the charging lines 6 and 7. Discharge lines 8 and 9 are shown connected to a common vessel 10, which in the case of cracking oils may be the so-called soaking drum. Each tube has a numeral 1 or 2 to designate the circuit to which the tube belongs, and a or sign to designate the direction of flow in the tube; The sign means that the fluid flows away from the observer and the sign means that the fluid flows toward the observer. The two rows are substantially horizontal and the individual tubes of the two rows are aligned in vertical columns of two tubes each with the possible exception of the extreme tubes which may have no corresponding tube in the other row. ,The flow in each branch of the double circuit is seen to be alternately through a top and bottom tube, the tubes of any one of the two rows being connected by header boxes to th'etubes in the nearest coluinns of the other row. The flow in the two branches is always in adjacent tubes and preferably in the same general direction in the furnace to insure equal heat pick-up in the two branches. Considering only pairs of adjacent tubes in any one row the flow may be parallelly in the case of Fig. 1 butit could be "opposite flow just the same.

Fig. 2 shows the same arrangement of tubes as Fig. 1 but the direction of flow in the individual tubes is observed from the other side of t e. furnace. that is from the left side if in Fig. 1 the How was observed from the right side of the furnace.

In most cases the furnace is divided by a bridge wall into a radiant heat section and a convection heat section. In such case the invention will be applied to the arrangement of the tubes in the radiant heat section.

In Fig. 3 the numeral 11 designates the radiant heat section, 12 the convection heat section of the furnace, separated from each other by the bridge wall 13. The tubes in the radiant heat section form a double circuit designated by numerals 1 and 2 and ending in the discharge lines 8 and 9. The lines 6 and 7 are connected to two sets of tubes in the convection heat section, designated by numerals 14 and 15. The separate feed lines 16 and 17 of the two sets of tubes in the convection heat section may be connected to two separate feed pumps or may be fed by one pump if so desired.

The size and shape of all the header boxes in the radiant heat section is exactly the same which, of course. is one of the advantageous features of the arrangement since it is not necessary to manufacture two or more different header boxes.

Having thus described my invention what I claim is the following:

1. Heat transfer apparatus, comprising a I combustion chamber, a series of connected tubes extending parallel to and spaced with respect to each other in vertically spaced substantially horizontal rows in the combustion chamber, the upper tubes being connected to the lower tubes in series, a second series of similarly connected tubes of the same internal diameter as the first mentioned tubes and disposed in the spaces between and substantially parallel with the first mentioned tubes in the rows, means for delivering substantially equal quantities of fluid to the inlets of the series, and means for discharging the fluid from the series.

2. Heat transfer apparatus, comprising a combustion chamber, a series of connected tubes extending parallel to and spaced with respect to each other in vertically spaced substantially horizontal rows in the radiant heat section of the combustion chamber, the upper tubes being connected to the lower tubes in series, a second series of similarly connected tubes of the same internal diameter as the first mentioned tubes and disposed in the spaces between and substantially parallel with the first mentioned tubes in the rows. means for delivering substantially equal quantities of fluid to adjoining inlets of the series whereby the fiuid flows through the pipes in parallel, and means for discharging the fluid from the series.

'3. Heat transfer apparatus, comprising a combustion chamber, a series of connected tubes extending parallel to and spaced with respect to each other in vertically spaced substantially horizontal rows in the combustion chamber, the upper tubes being connected in series to and horizontally offset from the series.

GEORGE B. COOK. 

